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Merge pull request #46 from ltcptgeneral/generate_trapezoid

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created generate_trapezoid.m
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Daniel Doan 2021-12-10 01:53:10 -08:00 committed by GitHub
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function x = generate_trapezoid(amplitude, frequency, phase, fs, duration, duty)
% GENERATE_TRAPEZOID: returns a matrix of sampled square wave
% CONTRIBUTORS:
% Daniel Doan: Author
% DOCUMENTATION:
% phase shift is in number of periods
% fs is the sampling frequency: how many sample points per second
% duration is time in seconds
% duty cycle should be a number between 0 and 1.
% duty of 0.5 would have 2 trapezoids in first half of each cycle
% example of wave with duty of 0.5, where the peaks are amplitude/2:
%
% ____
% / \
% / \ ________________
% \ /
% \____/
%
% initialize local variables from input arguments
n = fs * duration; % number of samples (length of matrix)
dt = 1 / fs; % sampling period: time between two sample points
% initialize a one dimensional zero matrix to be populated
x = zeros(1, n);
% populate the matrix
for i = 1:n
t = i * dt;
% periodic ramp from 0 to 1
% progression through a cycle
st = mod(frequency * t - phase, 1);
slope = (amplitude/2) / (duty/8);
if(st < duty)
if(st < duty/8 || st > 7*duty/8)
x(i) = slope * st;
else
if(st < 5*duty/8)
x(i) = amplitude/2 - slope * (st-(3*duty/8));
end
if(st < 3*duty/8)
x(i) = amplitude/2;
end
if(st > 5*duty/8)
x(i) = -amplitude/2;
end
end
end
end
end